<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        ul{
            list-style: none;
            overflow: hidden;
            width: 99px;
            background-color: gray;
            cursor: pointer;
        }
        ul li {
            float: left;
            font-size: 20px;
        }
        .box {
            color: yellow;
        }
    </style>
    <script src="jquery.min.js"></script>
</head>

<body>
    <div class="box">
        <ul>
            <li>☆</li>
            <li>☆</li>
            <li>☆</li>
            <li>☆</li>
            <li>☆</li>    
        </ul>
    </div>
    <script>
        const $ul = $("ul");
        $ul.on("mouseover","li",function () {
            $(this).text("★").prevAll().text("★")
        })
        $ul.on("mouseout","li",function () {
            $(this).text("☆").prevAll().text("☆")
        })
    </script>
</body>
</html>